A. Field of the Invention
The present invention relates to long-handled tools such as rakes, hoes, push brooms and the like, which are of the type generally used by persons in a standing position. More particularly, the invention relates to an improved push broom construction which utilizes a bowed handle to improve the ease of use and efficiency of the broom.
B. Description of Background Art
Long-handled tools such as rakes, hoes, shovels and the like are used routinely by people throughout the world in numbers too large to readily quantify. Such tools are used by farmers, gardeners, and homeowners, as well as other individuals. Included in the list of long-handled tools in widespread use is the ubiquitous push broom used by janitors and maintenance personnel to sweep floors, roadways and the like clean of dirt or debris. The construction of push brooms has remained little changed throughout the years, consisting essentially of a laterally elongated rectangular plan-view brush block having downward depending bristles, and a long straight handle which lies in a vertical plane perpendicular to the brush block. Most push brooms are constructed so that the handle is angled backwards from a vertical normal to the brush block and the horizontal footprint of the bristles in contact with a swept surface. With this construction, the handle may be more readily grasped and pushed forward or pulled rearward by the user to sweep a surface. However, even with the handle angled upwards and rearwards from the brush block, the thrust force exerted on the end of the handle grasped by the user is resolved into a substantially large component in the vertical direction, pushing down the tips of bristles against the swept surface. For example, with the longitudinal axis of the handle angled rearward 45 degrees from a vertical line through the brush block, thrust force exerted on the end of the broom handle by the user is resolved into equal horizontal and vertical reaction force vectors, equal to the thrust force multiplied by the sine and cosine of the inclination angle of the handle, respectively. Even for a more typical handle inclination angle of about 60 degrees, the vertical force exerted by the bristles on a swept surface is still half as large (cosine of 60 degrees) as the thrust force exerted on the handle by the user.
As a result of the substantial downward force exerted on a swept surface by the bristles of push brooms of prior art design and construction, substantial frictional forces, resist horizontal motion of the broom. This force is equal to product of the vertically downward component of the thrust force and the coefficient of friction between the bristle tips and the swept surface. The work required by the broom user to overcome the frictional reaction force is essentially wasted energy, since the purpose of sweeping with the broom is to move dirt with a minimum amount of force. As a result, push brooms of prior art design are difficult to use effectively by people with reduced strength, including women, children, and people with physical handicaps. Moreover, prolonged use of prior art push brooms, even by able-bodied persons, can cause muscle fatigue. For example, use of push brooms with a conventionally angled handle often requires that the user assume a somewhat stooped posture, to keep the bristles in flat contact with a swept surface, and/or to insert the broom head under obstructions. The stooped posture can cause back pain, and prolonged use of a push broom in this position can result in chronic back problems.
In apparent recognition of some of problems experienced in using conventional push brooms, Johnson, U.S. Pat. No. 4,958,407, discloses an Auxiliary Tool Handle comprising one or more looped auxiliary handles attachable to the straight handle of a push broom or a garden tool such as a rake, shovel, hoe or the like. The primary stated purposes of the auxiliary handle is to allow fingers of the user to grasp a portion of the auxiliary handle and exert forces directed substantially parallel to the fingers, rather than a slide-resisting force required when grasping a straight tool handle, which can cause fatigue and blisters. Since the curvilinear surface of the auxiliary handle curves away from the straight handle of a tool to which it is attached, it is possible to change one's grip and thereby lower the handle without bending over, to rake leaves under a bush, for example.
Hauser et al., U.S. Pat. No. 5,133,101, Jul. 28, 1992, discloses a mop handle having a cushioned end and opposed cushioned parallel side handles to reduce user strain.
Berti, U.S. Pat. No. 5,010,616, discloses a sweep broom with a handle slanted in the plane of the bristle block.
Other prior references known to the present inventors which relate generally to brooms consist of the following U.S. Patents: Bryant, U.S Pat. No. D321,793, Push Broom, Geffers, U.S. Pat. No. 3,891,339, Push Broom Handle Clamp, and Lammert et al., U.S. Pat. No. 4,538,318, Push Broom Assembly.
None of the prior art related to push brooms known to the present inventors is effective in reducing problems caused by the stooped postures required in using conventional push brooms having straight handles. The present invention addresses those problems.